Fuse



FeB. 21, 1933. v |CK FUSE ' Filed Aug. 10, 1929 mvtjvro c /gcSHU/i PA 779/ ATTORNEY cuit remains broken until Patented Feb. 21, 1933 UNITED STATES JOSHUA PATRICK, F DETROIT, MICHIGAN FUSE Application filed August 10, 1929. Serial No. 384,996.

This invention relates to a fuse plug and more particularly to a multiple fuse plug adapted to automatically shift from one fuse element to another when one fuse becomes burned out.

Heretofore when a fuse has become burned out it has been necessary to remove the plug and insert a new one. Very often such new plugs are not readily available and the cira new plug is obtained. It is, therefore, an object of the invention to rovide a single plug having a plurality 01 fusible elements, one of which completes the electrical circuit and to provide automatic means for bringing another of the fusible elements into the circuit after the fusible element has become burned out due to an overload in the circuit.

Another object of the invention is to provide a plurality of fusible elements on a cylindrical member and to intermittently rotate the cylindrical member into one of its several positions by an electrically operated thermostat.

Other objects and advantages of the invention will more fully appear from the following desciption taken in connection with the accompanying drawing, in which:

Fig. 1 is an enlarged sectional view illustrating one embodiment of my invention.

Fig. 2 is a sectional view on line 2-2 of Fig. 1.

Fig. 3 is a sectional view on line 33 of Fig. 1, parts being broken away and in elevation.

Fig. 4 is a sectional view on line 44 of Fig. 1, as viewed in a direction indicated by the arrows.

Fig. 5 is a sectional view on line 5-5 of Fig. 1, as viewed in the opposite direction indicated by the arrows.

Referring to the drawing wherein I have illustrated a preferred embod ment of my invention, the reference numeral designates an insulating portion having a metallic member 12 pressed into screw thread formation around a portion of the outer periphery thereof. The inside of the body portion 10 is hollowed out to receive the automatic mechanism here nafter more fully described.

One end of the body portion 10, which will hereinafter be referred to as the front end, is open and the opposite end of the body portion 10, hereinafter called the rear end, is closed, as indicated by a wall 14. A screw 16 is received in the wall 14 having its head 18 on the rear face of the wall 14 to form a contact member with the usual socket for receiving a fuse plug. The body portion of the screw 16 is provided with screw threads and a reduced portion 20 extends substantially the full length of the body portion 10 having its forward end threaded, as indicated at 22. A nut 24 is screw threaded on the body portion 16 and secures a bi-metal coil 26 between the inner face of the wall 14 and the rear face of the nut 24.

The bi-metal member 26 is spirally coiled and is adapted for expansion when it becomes heated. It will be understood that this coil is made by a well known process and'consists preferably of a sheet of brass and a sheet of steel held together as a single piece of metal.

On the reduced portion 20 of the screw I have provided an insulating member 28 and around the outer periphery thereof I have provided a heating coil 30. One end of the heating coil 30 is in electrical contact with the screw 16, it being held between the nut 35 24 and the rear Wall 14, or if desired it may be soldered to the nut 24 or screw 16. The opposite end of the coil 30 is in electrical contact with the screw threaded member 12, being soldered thereto as indicated at 32. On the forward end of the screw 16 a nut 34 is received on the screw threads 22 and an annular disc of insulating material 36 is received on a flange 38 of the nut 34. The disc 36 is rotatable on the flange 38.

The disc 36 is provided with a plurality of grooves 40 extending along the front face thereof, outer periphery and inner face and is also provided with a plurality of projections 42, having one edge 44 at right angles to the inner face of the disc 36 and another edge 46 extending diagonally from the apex of the projection 42 to the face of the disc 36. These projections are arranged between the grooves 40. A fusible element 48 is placed in each of the grooves 40, one end thereof being crimped in a circumferential groove 50 on the inner face of the disc 36 and the other end secured between the outer face of the disc 36 and the nut 24. If desired, these may be formed from a single stamping of fan shaped formation, having a plurality of radially extending members with the central portion having an opening to fit over the flange 38.

Secured on the forward end of the bi-metal coil 26 or integral therewith I have provided a non-metallic hook member 52 adapted for engagement with the face 44 of the projection 42. When the coil 26 becomes heated it will be understood that it is expanded and the hook member 52 moves angularly and rotates the disc 36 on .the flange 38 of the nut 34. The hook member 52 is in the form of an insulated pawl and thevdisc 36 with its projections 42 is in the form of a ratchet so that the two operate together .to intermittently move the disc 36 to a position for a new fusible element. The hook member 52 may be made of metal and insulated from the coil 26. 7

Another hook member 54 is provided on the opposite side of the plug and is in electrical contact with the screw threaded member 12, such as a connection 56 extending through the insulating material of the body portion 10. The hook member 54 is secured to the body portion 10 and is held stationary. The forward end of the hook member 54.- normally lies between two of the projections 42 'and is in electrical contact with one of the fusible elements on the inner face of the disc lVhen the plugis inserted into the usual socket, such as a conventional fuse plug 1 adapter, the current flows from the central.

portion of the socket through the screw 16, nut 34, fusible link 48, hook 54 and connection 56 to the screw threaded member 12 in electrical contact with'the other connection on the socket, not shown. When the current is overloaded the fusible element 48 is melted and the connection is broken, but due to the resistance of the heating coil 30 being shunted between the screw 16 and the screw threaded member 12, it heats and causes the bi-metal coil to be heated and thereby expand angularly, moving the disc 36 until the hook 54 rides over the face 46 of a projection 42 and springs into contact with another fusible element adjacent to the one melted.

The flow of current through the shunt coil 30 stops as soon as the connection is made through the new fusible link, due to the fact that the resistance through the screw threaded member 12, hook 54, fuse 48, nut 34 and screw 16 is low. The bimetal coil 26 then becomes cool and contracts to its normal position, engaging an ad acent pro ection on the inner face of the'disc 86, the hook 54 preventing rotationof the discf36 in the opposite sulating direction during the return movement of the hook 52. v p

It will be understood that while the drawing shows twelve fusible elements, any number may be used, depending on the size of .the fusible link and of the plug.

ing aplurality of fusible elements, an elec-' trical connection through one of said fusible elements, a heating coil shunted across the electrical connectionthrough said element, and means responsive to the changes in the temperature of said heating coil for changing the electrical connection from one fusible element to another.

2. A fuse of the class described comprising a body portion, an insulating member rotatably mounted on said body rality of fusible elements carried by said insulating member, an electrical connection through one of said fusible elements, a heating element in electrical connection heated by the currentwhenthe fusible element in electrical connection is broken, and a means responsive to the changes in the temperature of. the heating element for rotating said insulating member to bring another of the fusible elements into electrical connection.

3. A fuse of the class described comprising a body portion, an insulating member rotatably mounted on said body portion, a plurality of fusible elements carried by said inmember, an electrical connection through one of said fusible elements, a heatelement shunted across the electrical connection through one of the fusible elements, a member movable by the changes in temperature of the heating element in operative JQSHUA PATRICK.

portion, a plu- 

